Electrical system of distribution.



J. L. LFJGODBHIDGE.d

ELECTRICAL SYSTEM 0E DLSTRIBUTLOH.

/LPFLzcATxoN min JUNE 9,19%

aisened 19g Mig JOSEPHLESTER WOODBRIDGE, 0F PHILADELPHIA, PENNSYLVANIA.

ELECTRICAL SYSTEM OF DISTRIBUTIOT.

Application filed June 9, 1914.

To all whom t may concern:

Be it known that I, JOSEPH Lnsrnn lVooD- namen, a citizen of the United States, and a resident of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Electrical Systems of Distribution, of which the following is a specification.

My invention relates to systems in which' a variable speed dynamo supplies current to a consumption circuit requiring substan= tially constant voltage, and in which a storage battery is employed for supplying current to the circuit when the dynamo is shut down. My invention relates particularly to systems in which apparatus is provided for controlling the field excitation of the dynamo to produce constant voltage with variable speed. In vsuch systems it is customary to adjust the normal dynamo voltage at a value slightly above the floating voltage of the battery but not sutlieiently high to give the battery a high voltage gassing charge.

The object of my invention is to provide means in such a system for giving the battery a high voltage gassing charge at a time when the consumption circuit is disconnected and for automatically reducing the voltage to normal whenever the consumption circuit is connected to the dynamo and battery.

The accompanying drawing is a diagrammatic illustration of one embodiment of my invention.

In the drawing, D is the dynamo and F its field winding. The dynamo is connected to the circuit 1 2 across which a storage battery B is also connected. An automatic switch S is shown designed to connect the dynamo to the circuit when its voltage is suitable and to disconnect the dynamo when its voltage is below normal. This switch may be of any ot' the well 1Known types. Across the conductors 1 2 is connected a lVheatstone bridge lV comprising resistances 3, 4 and 5 connected as shown in two opposite branches, these resistances having a Zero temperature coellicient, and two resistances 6 7 in the other two opposite branches, these resistances having a high positive temperature coeiiicient, such as the well known iron wire ballasts The field F is connected across the two opposite points of the Wheatstone bridge as shown. The consumption circuit s shown at 8 and this circuit Specification of Letters Patent.

Patented Feb. 19, 1918.

serial no. 844,035.

may be connected to the circuit 1 2 by means of the switch 9. The two resistances 3 and l in one branch of the lVheatstone bridge are connected in series and a conductor 12 connects the junction point 10 between these two resistances with an eXtra contact clip ll on the switch 9, so arranged that when the switch is closed the resistance 4l is short circuited by conductors 1 and 12 and the corresponding blade of the switch. The design of the apparatus is such that when the resistance 4 is thus short circuited by closing the switch 9 the voltage of the dynamo is maintained at the normal value slightly above the floating voltage of the battery for all dynamo speeds above a certain critical speed. This result is accomplished by reason ot' the special characteristics otl the resistances comprising the bridge. The iron wire ballasts 6 and 7 exhibit a constant current characteristic for wide variations of impressed voltage within certain limits and the resistances 3 and 5 are so designed that when they are carrying a current equal to the constant current maintained by the resistances 6 and 7 the voltage drop across 3 or 5, respectively, will be one halt the desired limiting voltage across the conductors 1 2. Should the voltage across conductors 1 and 2 reach this desired limit the potential across the field F would be reduced to zero. For all values of voltage across the circuit 1 2 below this limit there will be a flow of current in the field F tending to increase with a slight reduction of voltage across the conductors 1 2, thus maintaining the voltage of the dynamo D substantially constant.

lVhen the switch 9 is opened the short circuit around resistance 4 is removed and there will be an additional drop in that branch of the YVheatstone bridge. This will lower 'the potential at the negative terminal of the iield F, causing additional current to liow through the field and raising the voltage of the dynamo D. Thus when the switch 9 is opened the voltage of the dynamo may be raised to give the battery a high voltage gassing charge, but whenever the consumption circuit 8 is connected by closing the switch 9 the voltage of the dynamo will be automatically reduced to normal -by shortcircuiting the resistance 4, thereby avoiding an abnormally high voltage on the consumption circuit.

1 do not desire to limit my invention to the particular' embodiment shown and described, nor to the particular means for controlling the dynamo Voltage used as an illus-f tration. Gbviously modiieations may be Iliade 1n the apparatus shown 'Without departing from the spirit of the invention.

Having described my invention what Iy claim and desire to secure by Letters Patent is- In combination, a dynamo and its field Windinga storage battery connected to the dynamo, a Wbeatst-one. bridgecomprising resistors of diierent temperature eo-etieients connected to the dynamo and to the ield Windingand adapted to. control the current in'said Winding to maintain substantially Copielvof ytllisr-pattmt.imagine.ebtaixied for five cents each, by addressing 'the Commissioner of Patenti,

Washington, im GJ 

